Laminated electric condenser



Nov. 7, 1950 A. LIECHTI 9 LAMINATED ELECTRIC CONDENSER Filed March 24, 1948 2 Sheets-Sheet l INVENTOR ,4; 55/27- L/ECHTI.

ATTORNEY Nov. 7, 1950 A. LlECHTl LAMINATED ELECTRIC CONDENSER 2 Sheets-Sheet 2 Filed March 24, 1948 INVENTCR A5521" Z/Et/rTL BY Ki. ATTORNE Patented Nov. 7, 1950 LAMINATED ELECTRIC CONDENSER Albert Liechti, Zurich, Switzerland, assignor to Micafil A. G., Zurich-Altstetten; Switzerland, a corporationoffi vitzerland a ApplicationMarch 24 ,;1948,Serial'No.16,822

In Switzerland February 19, 1947 f P The present invention relates to. electric condensers for voltagesover about 303 volts, having adielectric composed of layers of, insulating material whereby the thickness of the dielectric sigreater at its marginal portions than at its central portion.

' 2 Claims. (01.175 11 Till " The present application is a continuation in' part of my copending application Serial No. 7,608, filed Febill, 1948; It is an object of the present invention to provide a construction of electric condensers in which thedielectric strength of all regions of the "dielectric canbe fully utilized andglow effects "at the edges of the metallic layers are eliminated. This is accomplished by providing more dielectric matter atthe border regions of the condenser than at its central region.

It is a further object of the invention to construct the dielectric with thickened border re- -"gions in such a way as to avoid harmful deformation of the metallic layers at said regions. Ac-

cording to the invention packages of two or more narraw dielectric layers are placed adjacent to both sides of the edge portions of the metallic laminae. The Width of the individual narrow layers forming a package is diiferent andgraded to avoid sharp bends of the adjacent foils. The layers are made of oil impregnated material and have the same dielectric constants. V

Further and other objects of the presentinvention will be hereinafter set forth inlthe accompanying specification and claims and shown in the drawings which, by way of illustration, show what I now consider to be preferred embodiments of my invention.

In the drawings:

Fig. 1 is a transverse sectional perspective View of a condenser strip according to the invention before being coiled and pressed.

Fig. 2 is a diagrammatic transverse sectional view of a modified condenser strip according to the invention.

Fig. 3 is a diagrammatic transverse sectional view of another modification of a condenser strip according to the invention.

Fig. 4 is a diagrammatic transverse sectional view of a further modification of a condenser strip according to the invention.

Fig. 5 is a diagrammatic transverse sectional view of yet another modification of a condenser strip according to the invention.

Fig. 6 is a diagrammatic perspective illustration of a condenser constructed according to the invention and after being coiled and flattened.

Like numerals designate like parts in all figures of the drawings.

' In the arrangement of rolls and dielectric laminae diagrammatically-illustrated in Fig. 17 four --full width insulating layers 1 are disposed between twometallic laminae 2. At the edges of the latter, packages of two narrow dielectric V laminaeof different-width are placed.. directly adjacent both sides. of the foils and between the foils and the adjacent full Width layers. The strip of which Fig. 1 is a cross section, is then wound to form' a coil which is compressed and maybe flattened to a shape as illustrated in Fig. 6. To obtain the same arrangement of layers after Coiling four additional dielectric layers I must be provided, for example two below the metallic laminae and two above. 1 In the modification shown in-Fig; 1 the widest narrowinter mediary layers 3' are directly adjacent the foils 2 and the narrow intermediary layers tare placed -outside0f layers 3.

.iFig. 2, illustrates, diagrammatically, .,an ar- :rangement whereby the packages of intermediary small width dielectricgmaterial= consist each of I three different width:layers-indicated by dashe v dot lines whereby the narrowest layers 5 are directly: adjacent the metallic laminae 2 and the Widest, 6, are adjacent the full width layers. I, in-

.dicatediby dash-dot lines.

In 'themodification diagrammatically shown in Fig.6 the packages of intermediary layers consist'of four difierent widths and stepwise arrangedlayers .wherebyjin one'case, the widest,

-1, are adjacent one foil 2' and the narrowest, '8, are adjacent the'full width layers I, and'in the other case, the narrowest layers 8' are adjacent the other metallic lamina 2 and the widest, 1', adjacent the full width dielectric layers I.

The packages shown in any one of Figs. 1 to 3 may be used in an arrangement according to the other figures Without departing from the scope of. the present invention and the number of narrow layers forming one package may be changed to suit individual conditions.

It is known that the voltage at which a con- I denser can be operated is proportional to the square root of the thickness of the'dielectric; that the power that the condenser can accumulate is the product of tension and current and is proportional to the square of the ionization tension. V

Tests have shown that thickening of the border regions relatively to the inner region of a condenser by the factor n permits an increase of the operating voltage by the factor /n, provided that the insulating resistance of the dielectric in the central region withstands this increased voltage. The power of the condenser according to the invention is increased by the factor n.

If the thickened portions of the dielectric are I subdivided into halves between two metailic layers 9 by narrow intermediary strips of foil ID as shown in Fig. 4, as is done in conventional condensers, the permissible operating voltage is increased by the factor Vfi and the permissible operating power by the factor 2n. An increase of thickness of the border regions by, for. example, 40% whereby n amountsto 1.4, and insertion of narrow additionalmetallic linings results in a possible increase of the operating voltage by the factor /'2 1.4 and an increase of power by the factor 2.8. I

The narrow additional metallic linings need not consist of independent foils, the metal may be a 7 preferably steamed, pressed or sprayed to the respective. insulating 'layersi'whereby. the metal 'forming a narrow additional, coating at .both

borders of the same dielectriclayer may be conductively connected as shown iniFig. 4' whereby homogeneous distribution of electric tension is obtained over the whole mass of the-thickened dielectric. In the modification. shown in Fig. 4 the metallic laminae 9 project alternately from one side of the dielectric which produces better cooling than the modifications according to Figs. 1 to .3 where the foils are fully embedded in the dielectric.

Fig; 5 illustrates, diagrammatically, an arrangement according to the invention in which both side edges of the'metallic layers 2. are wrapped in supplemental dielectric laminae H,

H, I3 which are folded around theilongitudinal edges of the metallic-laminae. "The innermost laminae II is the smallest or narrowestand the After a condenser strip which is composedof layers whose relative arrangement may be as shown in Figs. 1, 2, 3,- 4, or 5 or equivalents -;thereof, has been wound to form a coil, the latter preferably flattened by the application of pressure in such a Way that not only the layers of the thickened border regions 14 but also of width of the laminae increases .gradually, l2 be- 'ing'widerthan II, and ]3'Wider' than H. In this Way a gradual thickening of the border regions of the condenseris produced and damage of layers 2 and I; I is'avoided when the'strip of which Fig.5 is a transverse section, iscom-' pressed.

the central region l5 are completely closely adjacent one another and a final configuration is obtained as per Fig. 6. The flattened coil, even with much thickened border regions, requires practically no more space than a condenser without thickened border regions though the coil with the thickened border regions can be loaded, electrically, up to four times as much.

While I believe the above described embodiments of my invention to be preferred embodiments, Iwish it to be understood that I do not desire to be limited to the exact details of design and construction shown and described, for obviousmodifications will occur to a person skilled in the art.

I claimf I l. A high tension electric roll condenser comprising, in combination; relatively thin metallic laminae, relatively thick dielectrics individually 'co'rn 'aosed ofa plurality of layers of oil'impregnated material and, individually disposed'lbe- ,tweensaid metallic laminae, and having an'inne'r region and border regions, and a small width dielectric placed on each side of said first dielectrics at a border region thereof, saidf'small Width dielectric being composed of atleast twosmall widthrlayers of oil impregnated, material and having the same dielectric constants.

2. An electric roll 'condenser fas definedlin claim -1, said different width insulating layers of each additional-dielectric being disposed icon.- 'secutively according to their widths for obtaining a graduated configuration at thesidefacing v the center of the condenser.

Italy June 25, 193.4 

